In general, a High-Definition Multimedia Interface (HDMI) source 102 (e.g., a source of audio and/or video data such as a set-top box, a digital media receiver, an optical media player, etc.) uses a unidirectional interface to transmit audio and/or video data to an HDMI sink 104 so that the audio and/or video data can be presented. FIG. 1 shows an example of an interconnection between HDMI source 102 and HDMI sink 104, where audio and/or video data is transmitted over TMDS channels 106 from an HDMI transmitter 108 of HDMI source 102 to an HDMI receiver 110 of HDMI sink 104. In such an implementation, there is no feedback to HDMI source 102 as to whether the audio and/or video data being transmitted to HDMI sink 104 is being presented by a display, speakers, etc., of HDMI sink 104. A signal or signals can be sent from HDMI sink 104 to HDMI source 102 over a hot plug detect (HPD) line 112, which can indicate to HDMI source 102 that an HDMI connection has been established between HDMI source 102 and HDMI sink 104. However, information related to whether HDMI source 102 is connected to HDMI sink 104 may not indicate whether or not HDMI sink 102 is in an “on” state, whether the output from HDMI source 102 is being presented by HDMI sink 104, or whether an HDMI input to which HDMI source 102 is connected is selected or active.
Certain HDMI sources can use a Consumer Electronic Control (CEC) line 114 to communicate with an HDMI sink and/or one or more other HDMI sources connected in a network via a CEC bus. Messages sent on the CEC bus using the CEC line 114 can be addressed to a particular physical and/or logical address of an HDMI device connected to the CEC bus (e.g., as described below). Particular types of messages that comply with the HDMI CEC standard can be sent over the CEC bus to a particular address (e.g., a physical address and/or a logical address) or as a broadcast message to all HDMI devices connected to the CEC bus.
However, the HDMI standard does not include a signal, on the CEC bus or through another communication channel, that allows HDMI source 102 to determine directly whether audio and/or video being output by HDMI source 104 is being presented to a user (e.g., using a television, an audio amplifier, speakers, etc.).
Accordingly, it is desirable to provide methods, systems and media for managing output of an HDMI source.